In recent years, vehicles that are equipped with a power storage device storing electric power and use the electric power stored in the power storage device to drive a motor, such as electric vehicles, hybrid vehicles, fuel cell vehicles, and the like have been attracting attention as environmentally-friendly vehicles. In such a vehicle, configuring the power storage device to be externally chargeable has also been under consideration. Further, in the vehicle described above, mounting a plurality of power storage devices to increase a traveling distance has also been under consideration.
With regard to a device or a method for taking electric power from a plurality of power storage devices, various proposals have been made so far. For example, Japanese Patent Laying-Open No. 2005-237064 (Patent Document 1) discloses a controller for a vehicle equipped with a plurality of battery packs. The controller obtains voltage values of high-voltage batteries in the respective battery packs, and determines priority in increasing order of residual capacities indicated by the voltage values. Then, the controller selects a battery pack determined to have the first priority as a battery for traveling.    Patent Document 1: Japanese Patent Laying-Open No. 2005-237064    Patent Document 2: Japanese Patent Laying-Open No. 2001-45673